A Relaxed Implant Bed: Implants Placed After Two Weeks of Osteotomy With Immediate Loading: A One Year Clinical Trial

The ideal goal of lifelike restoration has helped nurture new vistas in the art and science of implant dentistry. The protocol of “restoration-driven implant placement” ensures that the implant is an apical extension of the ideal future restoration and not the opposite. With the high predictability of osseointegration, the current trend is gearing toward the development of various implant placement protocols to enhance the patient's function, esthetics, and comfort.1 

The original Branemark implant protocol required a load-free and submerged healing to obtain predictable osseointegration to avoid the fibrous tissue encapsulation around the implant. However, recent research advocates precise preparation of the implant bed and adequate primary implant stability for more vital bone to be in contact with the implant interface, facilitating immediate loading.

It has been observed that preparation of an osteotomy followed by a waiting period of approximately 14 days enhances the surrounding tissue activity to its maximum level because collagen formation and neoangiogenesis represent a relaxed healing implant bed configuration. Therefore, a better method to enhance the alveolar binding capability before implantation is preferred.2 

The purpose of the present clinical trial was to conduct a clinicoradiographic evaluation around immediately loaded implants placed with newer placement modality comprising early osteotomy with implant placement delayed for 2 weeks.

In the present study, 6 patients (1 male; 6 female) with age range of 20–47 years (mean age of 33.5 years) irrespective of gender, with missing teeth in the anterior and premolar region were selected among the outpatient Department of Periodontology and Oral Implantology, Maharishi Markandeshwar College of Dental Sciences and Research, Mullana, based on the selection criteria.3,4 The inclusion criteria enrolled patients who were cooperative and motivated and who were missing one or more single rooted teeth. Sites with adequate amount of bone volume and bone quality with healthy, sufficiently sculpted, and stable soft tissue architecture were selected. Patients who were committed to pursue recommended plaque control and follow up regimen were considered based on the inclusion criteria. Patients excluded from the study included those with specific systemic disease for whom minor oral surgical procedure was contraindicated, those with parafunctional habits, and those with insufficient interarch space to accommodate the available restorative component.

After careful examination and clinical consideration, a standardized implant integration protocol for each site was planned that incorporated the principles of case selection, case evaluation, proper planning, preoperative preparation, optimal implant placement, and implant-specified definitive restoration.

The study was approved and accepted by the ethical committee at M.M. University, Mullana. The basic principle of health care to sign the consent form was accomplished by giving sufficient information about the proposed treatment protocol and the possible alternatives.

Meticulous presurgical evaluation, consisting of complete hemogram, determination of the specific soft tissue biotype and configuration, bone mapping, diagnostic casts (study and working model), clinical photographs, standardized periapical and panoramic radiographs, was done for each patient.

Patient preparation involved Phase I therapy, motivation, and reinforcement for oral hygiene regimen until satisfactory levels were achieved. With the help of diagnostic esthetic wax up on the study casts, selection and fabrication of the specific prosthetic components and construction of the surgical template for appropriate implant placement were completed.

Study models and working cast models were prepared for each subject for occlusal evaluation and record purposes. An esthetic wax up of the proposed implant site was constructed on the working cast model. Ridge mapping with impression tracing method was done to evaluate the buccolingual width of the bone for sites specific for implant placement.

With the help of intraoral periapical radiograph and tracing so obtained, the emergence profile and the shape of the restoration were reproduced on the surgical template prepared from transparent heat-cured polymerizing resin. First, the surgical template served the purpose of radiographic template when a hole was made through the middle of the incisal edge where gutta-percha cone was inserted to relate the ideal prosthetic axis on the intraoral periapical radiograph. Then, the hole was widened, which helped in guiding the lance drill during osteotomy for marking the optimal implant location on the alveolar crest in order to verify the implant position during placement.

Oral disinfection was performed using a 0.2% chlorhexidine digluconate mouthwash as a presurgical oral rinse. A minimally invasive paracrestal mucoperiosteal flap was raised at the planned site for osteotomy preparation (Figures 1 and 2). This was followed by surgical template-guided osteotomy (Figures 3 through 6) followed by flap suturing (Figure 7) without the placement of implant, giving time for the socket to heal from trauma and heat.

After waiting for approximately 2 weeks (Figure 8), a soft tissue punch (Figure 9) was used to expose the previous surgical osteotomy site for implant placement. After slight curettage and irrigation with saline, fixtures of required dimensions were inserted with the help of a torque-controlled hand wrench (Figures 10 and 11) with an insertion torque of 30–35 Ncm to ensure primary stability. After achieving primary stability, straight rigid abutments (Figure 12) of recommended dimensions were screwed with the help of a torque-controlled hand wrench.

Antibiotic (amoxicillin and cloxacillin, 500 mg) and anti-inflammatory therapy (ibuprofen, 400 mg) 3 times a day for 5 days was continued. After 2 weeks, interdental brushing was demonstrated and recommended after every meal.

After placement of abutment, impression was made with rubber base impression material and sent to the laboratory where esthetic and nonfunctional acrylic provisional restoration was fabricated. After about 24 hours, provisional restoration was cemented with temporary zinc oxide eugenol cement. It was assured that the provisional restoration was kept out of contact in centric as well as eccentric occlusion (Figure 13).

After about 6–8 weeks of implant placement, the process of fabrication of definitive restoration was taken up, after a clinical and radiographic evaluation of the implant.

Provisional crowns were removed for making the final impression. A plastic impression cap was seated onto the abutment, and a final impression was made using additional silicone impression material to obtain abutment level impression (Figure 14). Abutment lab analog was then seated into the impression cap (Figure 15), which got transferred to the cast when the impression was poured with type IV dental stone. Metal trial was accomplished (Figure 16) before the fabrication of porcelain fused to metal definitive restoration to evaluate occlusion in centric and eccentric contacts.

All of the porcelain fused to metal definitive restorations was cemented using glass ionomer cement (Figure 17).

Follow-ups of 6 and 12 months were scheduled with definitive restoration as baseline incorporating assessment of clinical and radiologic parameters (Figures 18 through 22) around the implants. Clinical parameters like keratinized mucosa index, peri-implant probing depth, implant mobility,5 and radiographic evaluation of mean marginal bone were assessed. All of the radiographs were taken with long cone paralleling technique with exposure time of 0.8 seconds. All of the obtained radiographs were digitalized using flatbed double width photoscanner at 300 dpi, 8 bits, and 256 grey shades and saved as bitmap images. For each digitalized radiographic image, measurements were made from the inferior edge of the implant collar (first thread) considering as a reference point to bone-implant contact with the help of image tool software (UTHSCSA, version 3, University of Texas Health Science Center in San Antonio). This helped in assessing the amount of bone loss that occurred over the period of the study on the mesial and distal aspect of the implant.

The scores were statistically analyzed by calculating their mean values and standard deviation. The mean difference between the intervals was calculated for each group using paired sample t test, and Wilcoxon signed rank test was used to calculate z and p values for its clinical significance.

No implant was mobile during 1 year in function giving an overall survival rate of 100%. There was an increase in width of keratinized mucosa from baseline to the 12-month interval with a mean difference of 0.17 ± 0.49 mm, which was statistically not significant (Tables 1 and 2). The peri-implant probing depth decreased from baseline to the 12-month interval with a mean difference of 0.29 ± 0.24, which was statistically not significant (Tables 3 and 4).

On radiographic analysis, average bone loss during the follow-up period was 0.4 mm after the placement of definitive prosthesis until 1 year in function. The total bone loss during the observation period did not differ significantly among the intervals (Tables 5 through 8).

The esthetic and functional demands for the replacement of missing teeth have always been a major focus of oral rehabilitation. With the ever increasing demand for esthetics, the interim period of edentulousness even after implant placement can cause psychologic, social, or functional problems, especially if the edentulous area is in the appearance region. Consequently, immediate loading of dental implants was introduced to achieve triumph over original Branemark protocol, which not only includes nonsubmerged 1-stage surgery, but actually loads the implant without compromising osseointegration.

Implant stability is determined by the biomechanical properties of the bone, the surgical technique, the implant design, and the healing capacity of the traumatized bone. Surgical trauma and anatomic limitations are the most important factors for early implant losses, whereas jawbone quality, volume, and overload are major determinants for late implant failures. The impact of these factors on implant failure rate can be altered by modifying the surgical technique.6 An adaptation of the surgical technique, the loading protocol or design, and surface characteristics of the implant could improve the clinical outcome.

However, aside from the problems of discomfort, inconvenience, and anxiety associated with the waiting period, the original protocol appeared to have 2 main disadvantages concerning bone and soft tissues. Ericksson and colleagues7 showed that causes of surgical trauma include thermal injury and mechanical trauma that may cause microfracture of bone during implant placement, which may lead to osteonecrosis and fibrous tissue encapsulation around the implant. Sharawy and colleagues8 concluded that bone-cutting procedures produce a local rise in temperature due to frictional heat. Even with saline irrigation, temperature adjacent to the drills may often reach 60°C and above. It is generally agreed that temperatures above 56°C to 60°C are deleterious to the bone tissue as they give rise to the denaturation of hard tissue proteins. It was observed that the temperature in the bone next to an implant drill during preparation of an osteotomy was related to the rotations per minute (rpm) of the drill. Misch and colleagues9 in a review article concluded that the temperature in the bone was affected by the rotations of the drill as 2500 rpm produced the least heat and maximum temperature increase was observed at 1250 rpm. The effect was revealed by early formation of granulation tissue and early resorption of the margins of the bony defect. Accordingly, controlling heat generation will help avoid thermal bone necrosis that may influence bone healing.

Misch and colleagues9 reported that higher bone strain (change in length of bone divided by the original length, measured in percentage) adjacent to implant surface leads to pathologic overload and fibrous tissue formation. They also concluded that surgical trauma may be reduced by decreasing the heat generation and pressure necrosis.9 Further, it was also concluded that the initial healing process appeared to be accelerated with lower heat by use of water coolant, reduction in drilling time, and high speed cutting.2 

Based on the concept of bone healing, it was also observed that bone healing after osteotomy passes through 3 stages: inflammation or granulation tissue formation, fibrous tissue formation, and finally maturation with remodeling of bone.2 Recent research advocates precise preparation of the implant bed and an adequate primary implant stability for more vital bone to be in contact with the implant interface, facilitating immediate loading.

According to a histological study by Ogiso M et al, maximum bone resorption occurs at the margins of the bone defect by the second week and rapid formation of new trabecular bone starts by the third week in an attempt to repair the defect.10 Thus, offering a relaxed healing implant bed ready to receive a fixture is obviously preferable to inserting a fixture in a traumatized and heated site. Therefore, a better method to enhance the alveolar binding capability before implantation is preferred.

The present clinical trial with newer implant placement modality confirmed the reported clinical feasibility of the technique as demonstrated in a previous clinical study by EL Attar et al2 and a histologic study by Ogiso et al.10 Within the limits of the present study, results indicated implant stability up to 1 year after implant placement.

The preparation of esthetically appealing and implant-protected provisional restorations facilitates fabrication of the final implant-supported crown. The provisional restoration also moulds and manipulates the soft tissue and acts as a blueprint or template for the final crown.11 

Although flap reflection is the ideal approach for implant placement, esthetic outcomes are definitely compromised. Cosmetic appearance and functional properties of gingival attachment around the abutment are rapidly and completely achieved with a natural appearance. Accordingly, adopting the punch technique alleviates associated surgical morbidity such as postoperative pain, swelling, and discomfort and thereby enhances patient acceptance.2 

The clinical and radiographic documentation of early osteotomy with implant placement delayed for 2 weeks indicates better results as primary healing of the bone was allowed prior to implant placement. The use of immediate loaded implants has obvious advantages because patients can be rehabilitated with functional crowns for immediate function and esthetics.

Offering a relaxed healing implant bed configuration is clinically acceptable that needs comparison with immediate implant placement in a heated and traumatized osteotomy site. The presented timing of implant insertion (2 weeks after osteotomy preparation) needs further future research work in preparing implant beds.

Therefore, further studies are required to find indications based on surgical, host, implant, and occlusal conditions for early osteotomy with delayed implant placement and also ascertain its advantages over the conventional approach. Additional data will provide clinicians and researchers improved foundations for decision making relative to selecting the most appropriate implant placement protocol.